Which dog is the bad one?

We have 2 dogs and sometimes when we leave them inside when we're not home they get into things. It can be a loaf of bread left on the counters to them being on the furniture. We want to punish them but which one? Is there some kind of sign for which is the guilty one? They both will not greet us when we come home whenever something bad has happened. Help, I feel bad for punishing them both, cause I'm pretty sure they don't conspire together.